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1. NO BLATANT PIRACY. This includes reproducing homebrew less than 10 years old, with the exception of free software.2. No advertising your reproductions, with the exception of free software.3. Be nice. See RFC 1855 if you aren't sure what this means.

Since I found the dumped "Rockman 6-in-1" multicart I was thinking about recreating the cartridge on existing donor MMC3 board. But I lack the knowledge to figure out the additional hardware needed for it so I want to ask for your help. It shouldn't be very hard, as MottZilla, who helped me to make my own dump of that cartridge, already found out everything about the software. Here are his quotes from the TapeDump topic:

MottZilla wrote:

Some bits are speculated until more testing can be done. PRG is probably concrete but CHR is a bit fuzzy. I think the upper nibble of $5010 and $5012 are related to CHR configuration.

$5012 - CHR Chunk Base SelectxxBB-xxxx BB = Selects 128K Base of CHR-ROM for MMC3 Only values 00 and 10 are used but bit 0 may be valid too.

On Powerup PP of $5010 is zeroed, BBB of $5011 also zeroed. This causes the first 512K of PRG-ROM to be seen by the MMC3 which puts the Menu program in control.

$5011 really controls upper address lines on the PRG-ROM. $5010 controls address lines too, by deciding which ones the MMC3 can control and which ones it holds in a constant state to effectively set bounds for the ROM data seen by the MMC3.

That should cover most of the mapper and how it works.

---

Stuff about hardware. I'm not sure this is all exact as I'm no hardware expert.

PRG-ROM ConnectionsA16 and Below Connect Normally to MMC3

A17 - HELD HIGH in 128K Size Mode, otherwise connects normallyA18 - Connects to MBR if Size isn't 512K. If it is then it connects to MMC3A19 - Connects to MBRA20 - Connects to MBR

MBR being Master Bank Register. It controls the upper PRG lines. The upper most 2 are always connected to the MBR. A18 is used in 256K and 128K PRG modes by the MBR. In 512K mode the MMC3 needs this as the ROM is 512K and needs that to switch between the first and last 256K of data. A17 connects normally to MMC3 unless the mode is 128K in which case its I think held high (+5v) so the lower 128K of the selected 256K block is all that is visible. This is used for Rockman 1.

I think all this is correct. CHR-ROM has a similar setup. I imagine you could built your own cartridge with a TxROM cart and additional hardware for the MBR.

The cartridge needs 2048kB for PRG and 512kB for CHR. CHR won't be hard to add, since 27C401 will be okay for that, but PRG is harder, and since my EPROM programmer is not capable of burning EPROMs with more than 32 pins, it would be best if the PRG ROM gets splitted in even+odd parts to two 27C801 EPROMs. I'm really looking for some easy (can be hand-drawn) schematics of this.

Lastly, for the link to the rom dump on that chinese website, click first result of this search or contact me via PM, as I don't want to post that link here. The chinese dump was emulated by CaH4e3's mapper-modified version of FCEU. My dump was emulated by MottZilla's personal unreleased emulator. The cartridges used by me and those chinese guys are the same.

Shouldn't be hard is relative, what's easy to emulate isn't necessarily easy to put into hardware. Since you need help I wouldn't make such assumptions It looks like nearly 10 chips unless you use programmable logic, and it will require adding in a CHR RAM. Reworking all that into a donor board, easy? I think not. I also don't think it's very economical compared to just buying another multicart or even designing another one that's more hardware efficient.

I'm not against using programmable logic, as far as it's relatively easy to get the programming inside (I have a selfbuilt 74188 and 74287 programmer, if that helps, if not, here is what my Eprom programmer looks like, maybe it can be used to programm something different). CHR RAM is also not a problem, I have spare 8kB and 32kB SRAMs.
This is not a question of money, but the original pirate multicart itself is pretty rare (and fragile, since it's a glob-top).

If you reread, he says either two 27C801 (8 meg) eproms or one 16 meg 27c160. Either works except that you will need another chip or atleast part of one to control chip select between the two I think.

Farid has built a MMC3 multi cart from a pirate cloned MMC3 chip before as I recall. So he should have a good idea of how you could reconstruct this mapper.

Farid, what jpx wants to know is how to wire up the TTL chips and eproms and sram and a MMC3 mapper so he can recreate it. I don't think he knows much about the functionality of the logic chips, which is what he is asking for help with. Not necessarily understanding the logic but getting a wiring diagram so he can build it.

The cartridge needs 2048kB for PRG and 512kB for CHR. CHR won't be hard to add, since 27C401 will be okay for that, but PRG is harder, and since my EPROM programmer is not capable of burning EPROMs with more than 32 pins, it would be best if the PRG ROM gets splitted in even+odd parts to two 27C801 EPROMs.

You can see I knew all that, and no, I cannot use 16-bit EPROM because it has 42pins and my programmer doesn't support that, as I mentioned.
You don't need control chip to use two 27C801, you can even use the "sandwich" ("piggyback") method to easily connect them together (to build yourself a 27c160 from them). Trust me, I learned my part of that with 16-bit consoles, where I had to use 8-bit chips instead of 16-bit, because of the limitations of my programmer (check my NeoGeo MVS bios replacement here)

Sorry, I don't want to struggle anymore, thanks MottZilla for trying to help. I know enough to build almost anything if the proper schematics is available, I have my experience with building cartridges from scratch for Sega Mega Drive, Master System, Atari and even Watara Supervision. And I know enough about NES/FC cartridges too.

I would be really thankful if somebody can figure out the TTL logic and draw some simple schematics for connecting it all together.

Last edited by jpx72 on Tue Dec 20, 2011 1:43 am, edited 1 time in total.

I am not an expert and don't know much about software aspect and last time I had a hard time to understand about registers and how they really function! I just make cartridge by reverse engineering the hardware of my own pirate cartridge and then mix it with my imagination, and I love doing it! Here is my imagination about this cartridge :
Edit : Sorry this diagram is wrong!

For second time : I need to see the picture of the cartridge which is glop top to make a better imagination

Last edited by FARID on Tue Dec 20, 2011 1:37 am, edited 1 time in total.

PS: The search won't point you to the actual romdump, I was searching for it with the help of google translator on some chinese sites and it took me quite some time. If you need the link to the romdump itself, go to the first result of this search.

Ok very good. From now on you have to rely on some other info. You need to find out about special lines. You can also ignore identifying exactly some of lines. For example it is not necessary to find out which line is really CHR A17 because we know that lines from CHR A10~A18 connect directly to AX5202P so you can mark those 9 lines which directly come from CHR and go to AX5202P, in generally A10~A18.

I am not sure about MMC3, I feel that it is not AX5202P!
Try to find out which pin is PRG A19 and CHR A19. It should be a line which is shared between PRG + CHR + MMC3. If no such a line then MMC3 is not AX5202P.

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